Duplex smelting-furnace.



No. 810,063. PATENTED JAN. 16, 1906. R. LINDBMANN.

DUPLEX SMBLTING FURNACE,

APPLICATION FILED MAR. 10, 1905.

Fig. I.

UNITED STATES PATENT OFFICE.

DUPLEX SIVIELTING-FURNACE.

Specification of Letters Patent.

Patented Jan. 16, 1906.

Application filed March 10, 1905. Serial No. 249,446.

To all whom it may concern:

Be it known that 1, ROBERT LINDEMANN, a sub ect of the German Emperor, residing at 59 Martinistrasse, Osnabruck, Germany, have invented a new and useful Improved Duplex Smelting-Furnace, of which the following is a specification.

This invention relates to a crucible smelting-furnace especially for the smelting of cast-steel in crucibles, in which process a relatively high heat (of2,000 Celsius and upward) must be maintained in the furnace for two or more hours.

The object of the invention is to provide a furnace of this type in which within a short time a very high degree of heat can be obtained sufficient, first, to produce a malleable and a weldable steel which can be cast in molds, and, secondarily, to utilize the very great waste heat of such a furnace as advan tageously as possible. In order to attain this double purpose, the smelting-furnace is constructed, according to this invention, as follows: The roof of the smelting-furnace properthat is, of the chamber in which the crucibles are placed-is double-walled, and by means of the specially-arranged horizontal spaces between air under pressure introduced from above is conducted in a serpentine zigzag track to the under side of the grate, whence it rises to the crucibles through the fuel and then passes into a furnacehearth attached to the crucible hearth proper, which hearth is constructed like a foundry-furnace and in which cast metal requiring a lesser heat for fusion than the material in the cruciblessuch, for instance, as cast-ironis melted by the waste heat of the cruciblefurnace proper.

A furnace of this kind is illustrated in the accompanying drawings.

Figure 1 is a vertical longitudinal section through the axis of the furnace on the line C ,D of Fig. 2.

Fig. 2 is a horizontal longitudinal section on the line A B of Fig. 1.

The space for the reception of the crucibles a, which stand upon the grate b, is surrounded by a wall of fireproof masonry c, which has a double-wall iron casing (1. Between the walls of the casing baffles e, which are open at one side and preferably of U-shaped iron, are arranged as intermediate walls, so that the open side of each adjacent frame is arranged opposite to that of the frame placed above it. At the top of this double-wall space there is a tube f for the introduction of the air under pressure, and at the center of the orifice of f (at the uppermost frame e) a vertical plate 9 is set, which plate is designed to divide the entering current of compressed air and turn it toward both sides, Fig. 2. Under the grate is a plate arranged with perforations i and under this a hinged damper m, kept closed by means of catches 7c and serving to close the furnace-chamber underneath air-tight. The furnace-chamber is arranged to taper above the double-wall cover and be closed by means of the lid at, closing the charging-opening. From the upper part of the furnace-chamber a passage 0, with or without intermediate walls, leads into the chamber of the smelting-furnace p, which is provided with a tap-hole g, a peep-hole r, and charging-opening s. From the crucible-furnace the flue t leads to the chimney u. The forced blast takes the course indicated by the arrowsthat is, it passes through the inlet f, divides against the plate g, passes into the cover-space over the uppermost frame 6, so that at the hinder side it enters the next lower space, and thus passes in a zigzag or serpentine track down the furnace-wall 0 into the space surrounding the perforated plate The compressed air is thereby well heated and serves at the same time to cool the fur nace-wall c. The air then passes through the apertures i from all sides into the interior of the furnace, then rises upward through the fuel packed around the crucibles, and effects the smelting at a very high heat. The still highly-heated mixture of combustion-gases and air then passes through the flue 0 into the hearth of the foundry-furnace, passes over the hearth, and effects here in the wellknown manner the smelting of cast-iron or other material, which can be run off when molten through the run-off hole q, and the combustion products finally pass into the outlet u. rectly discharged into the outlet through a usual flue, experience has shown that it would then act injuriously upon the flue and the outlet and cause frequent repairs and &c., whereas in this manner by the construction of the outlet-flue of the crucible-furnace in the form of a foundryfurnace not only is this drawback obviated, but also at the same time the large amount of waste heat can be utilized directly for the smelting of cast-iron, so that the entire operation of the cruciblefurnace becomes a very economical one.

If the very high waste heat were di-v other troubles in working, with waste of time,

What I claim is 1. In a duplex smelting-furnace, a primary hearth capable of being intensely heated, an inner refractory wall around said hearth, an outer metal casing surrounding said inner wall, air-passages in said outer casing, an airinlet communicating with the said air-passages and with a source of air under pressure, a baflie-plate for directing the admission of the air in opposite directions from the said air-passa es round the furnace to the said hearth, air-holes at the base of the primary hearth for admitting the air under pressure thereto, a movable plate adapted to shut off hermetically the ash-pit from the primary hearth, and a secondary hearth alongside the primary hearth and capable of being heated by the waste heat from the primary hearth.

2. In a duplex smelting-furnace a primary hearth, the air-inlet f, the hollow metallic jacket (1 surrounding'said hearth, baflies e and dividing-plate gin said metallic jacket adapted to divide the blast and pass it in serpentine or zigzag directions around said hearth and discharge the heated blast beneath said hearth, the plate having perforationsifor admitting air to the fuel on the hearth, the hinged plate m adapted to control the admission of air to the primary hearth from below the same, a secondary smelting-hearth and an escape to the outer air for the combustion products.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ROBERT LIN DEMANN.

Witnesses:

PETER LIEBER, SOPHIE BECKER. 

